The present invention relates in general to alignment instruments used in construction, and in particular, to laser transmitters capable of operating while oriented horizontally or vertically, and which are suitable for use in confined spaces.
Reference laser beam systems are used in numerous surveying and construction applications. In one such application, a laser beam transmitter is used as a direction and grade reference during the installation of sewers and other pipes. Basically, a pipe laser provides a stationary, collimated beam of light that is directed axially along the centerline of a pipe installation. The light beam serves as a visual guide in order to maintain individual sections of pipe in a straight line at a particular grade. A laser beam target is typically placed within each new section of pipe being set into place. The target and the new section of pipe are manipulated until the collimated light is centered on the target. Upon centering the target and securing the new section of pipe in position, the target is removed and relocated to the next new section of pipe.
During construction of pipe systems, it is common for a number of manholes to also be installed. Manholes, also referred to interchangeably herein as hubs, are an important aspect of the pipe system. Hubs serve as repair stations for necessary maintenance and upkeep after the pipe system has been installed. Hubs may also be used to collect and reroute sewage, couple pipes of different diameter together, change pipe slope or elevation and reference the line, grade and depth of the pipe.
Pipe sections used for sewers are typically large, generally cylindrical sections of pipe. For example, sewer pipe sections are typically at least six inches (150 millimeters) or larger in diameter. Hubs are typically anywhere from 3–5 feet (91 centimeters to 152 centimeters) in diameter, and may be positioned as deep as 30–40 feet (nine meters to twelve meters) into the ground. However, in certain locations about the world, such as in Japan and Sweden, the diameter of the sewer pipe is being greatly reduced. Also, traditionally large hubs are being replaced by single piece plastic hubs, referred to as clean outs. Unlike traditional hubs, clean outs have an entry diameter of approximately 12 inches (300 millimeters). Comparatively, a typical hub is typically 24–30 inches (600–800 millimeters) in diameter. Due to the space constraints of the clean out and the associated relatively small diameter pipe sections that connect thereto, it is not always possible to orient a typical pipe laser in a clean-out so as to direct the laser beam in a desired direction. This is because pipe lasers are typically long, generally cylindrical devices that cannot be rotated or easily positioned within the confined spaces of the new clean outs. Accordingly, typical pipe lasers cannot be used to lay pipe systems that utilize the smaller clean outs.